Iterators and Generators

Iterators

• Don't use iterators. Prefer JavaScript's higher-order functions like map() and reduce() instead of loops like for-of. eslint: no-iterator

Why? This enforces our immutable rule. Dealing with pure functions that return values is easier to reason about than side effects.

const numbers = [1, 2, 3, 4, 5];

// bad
let sum = 0;
for (let num of numbers) {
sum += num;
}

sum === 15;

// good
let sum = 0;
numbers.forEach(num => sum += num);
sum === 15;

// best (use the functional force)
const sum = numbers.reduce((total, num) => total + num, 0);
sum === 15;

Generators

• Don't use generators for now.

Why? They don't transpile well to ES5.